Load testing

Loading +5 V SB

As always, all load testing is done according to our testing methodology. The efficiency of this unit’s stand-by supply is slightly lower, as could be expected from a cheaper unit. Though about 73 % is still a nice result. The ripple is very nice and voltage regulation is still within 3 % which corresponds with the mainstream price.

Output (W)

Load (A)

Voltage (V)/ ripple (mV)

Input (W)

Efficiency/power factor

0

0

5.132/6.600

0

—/0.022

14.51

2.90

4.999/4.000

19.68

73.8 %/0.514

16.90

3.40

4.976/4.000

23.14

73.0 %/0.531

+5 V SB ripple (left to right): 0 A; 2.90 A; 3.40 A

Hold-up time

As we can see on the oscilloscope screenshot, the hold-up time of the Volcano 750 Gold +12 V rail is not very long, just 12.44 ms.

The hold-up time of the power good signal is totally broken, the voltage goes slightly up instead of being pulled down and stays there for almost a second. Definitely something bad with the unit, I would expect some SMD transistor or maybe some gate in the secondary supervisor to be bad.

So I have requested a second sample to see whether it was isolated incident, or it showed flawed design. This piece works OK, the power good signal hold-up time reached 14.60 ms so the first unit was definitely defective.

The voltage hold-up time is slightly shorter which is not completely right, on the other hand the unit does not even reach ATX minimum with either of the hold-up times so…

For the voltage to stay within spec I had to shorten the interruption time though, to 13.50 ms. This is not really high value but it is at least still well over my absolute minimum of 10 ms so it should still work well even with cheaper or older UPS.

Combined loading

Combined loading was mostly OK for the Volcano 750 Gold. Firstly, let’s talk about the voltage regulation. As this is a 12V unit with DC–DC buck regulators, the results are expected to be better than of ordinary group design platforms which we still find in mainstream. The +3.3V rail voltage started quite high, at 3.417 V. That is more than 3.5 % over nominal, not that great of a result, but all voltages stayed in spec and most of the rails in much tighter regulation actually. Load regulation is also reasonable. That incudes the −12V rail where some current competition series still have problems. So for me this is OK.

Output power

Load/ voltage +5 V SB

Load/ voltage +3.3 V

Load/ voltage +5 V

Load/ voltage +12 V

Load/ voltage −12 V

Input power

Efficiency/ power factor

3.9 %/ 29.34 W

0 A/ 5.126 V

0.020 A/ 3.417 V

0.405 A/ 5.075 V

1.867 A/ 12.162 V

0.391 A/ −11.701 V

40.23 W

72.9 %/ 0.779

20 %/ 152.35 W

0.545 A/ 5.087 V

1.501 A/ 3.396 V

2.312 A/ 5.047 V

10.60 A/ 12.095 V

0.392 A/ −11.762 V

175.5 W

86.8 %/ 0.943

40 %/ 300.53 W

1.033 A/ 5.049 V

2.88 A/ 3.401 V

3.43 A/ 5.023 V

21.9 A/ 12.039 V

0.389 A/ −11.902 V

336.9 W

89.2 %/ 0.970

60 %/ 452.52 W

1.90 A/ 4.993 V

4.06 A/ 3.357 V

4.90 A/ 4.995 V

33.4 A/ 11.979 V

0.397 A/ −12.150 V

510.7 W

88.6 %/ 0.980

80 %/ 596.29 W

2.37 A/ 4.952 V

5.45 A/ 3.333 V

6.70 A/ 4.964 V

44.3 A/ 11.922 V

0.400 A/ −12.426 V

682.1 W

87.4 %/ 0.983

100 %/ 754.13 W

2.84 A/ 4.931 V

6.80 A/ 3.329 V

7.83 A/ 4.951 V

56.5 A/ 11.919 V

0.416 A/ −12.770 V

868.9 W

86.8 %/ 0.987

The efficiency is nice. As usual, my instruments measure 3 percentage points lower compared to high-end DC measuring stations. So the maximum may really be over 90 % for this model. On average it is very close to 80 PLUS Gold average (88 %) so I think the unit passes OK here, too.

Combined loading ripple

The ripple values of the Volcano 750 Gold are outstanding, especially for its mainstream price. All three minor rails stayed under 10 mV the whole time (so 18 out of 30 values are sub-10 mV), the +12 V rail managed to keep under 20 mV while the negative rail crossed 30 mV, but only with full load. Very nice, I think this being a mainstream unit, it is worth 3 points.

Crossloading, overloading

Crossloading tests went OK, as could be expected from such platform. The only minor flaw I found is that the +3.3V OCP was set too strict, my loader resistors were drawing slightly over 20 A while the unit was shutting down as soon as the load dropped to about 19.95 A. I have not tested the second sample for this though. So the thing is, the Volcano 750 Gold may actually not even deliver rated 20 A, depending on the OCP settings. This is especially funny when the original SAMA Forza 750W is rated 24 A @+3.3 V and only 15 A @+5 V, while here it is 20 A for both. So maybe there is a bug in the OCP settings somewhere…I think this is worth extracting a symbolic point for this. On the other hand there are OCPs, despite Modecom’s specifications which do not state so.

Output power

Load/ voltage +5 V SB

Load/ voltage +3.3 V

Load/ voltage +5 V

Load/ voltage +12 V

Load/ voltage −12 V

Input power

Efficiency/ power factor

13 %/ 99.41 W

0.551 A/ 5.065 V

19.95 A/ 3.357 V

0.416 A/ 5.006 V

1.890 A/ 12.124 V

0.396 A/ −11.756 V

130.4 W

76.2 %/ 0.924

17 %/ 131.03 W

0.538 A/ 5.066 V

1.478 A/ 3.363

19.46 A/ 4.934 V

1.889 A/ 12.100 V

0.383 A/ −11.644 V

159.2 W

82.3 %/ 0.937

98 %/ 738.60 W

0.519 A/ 5.049 V

1.451 A/ 3.370 V

1.600 A/ 5.009 V

60.3 A/ 11.909 V

0.390 A/ −12.703 V

844.8 W

87.4 %/ 0.987

128 %/ 957.56 W

3.283 A/ 4.862 V

19.02 A/ 3.259 V

18.39 A/ 4.831 V

66.3 A/ 11.844 V

0.413 A/ 13.335 V

1153 W

83.1 %/ 0.991

The combined limit for OPP was kinda problematic to achieve. Both lower rails being limited to about 20 A and having my +12V draw limit (in the meantime increased though), I could have only loaded the unit with about 950 W. It was close to shut down in the end though as the unit started cycling, which would suggest there is actually OTP present. As the supervisor had intermittent signal from OTP sensor (thermistor), it was showing this behaviour, as the unit cooled down, things returned to normal. So the unit can deliver the power and actual OPP (or +12 V OCP) limit is higher, but it has cooling problems when overloaded. The −12V voltage also rose too high though otherwise it was working OK within specs.

Crossloading, overloading ripple

The ripple is still very low, impressive results, let’s award this by a further extra point.

Output %

Ripple +5V SB

Ripple +3.3 V

Ripple +5 V

Ripple +12 V

Ripple −12 V

13

5.600 mV

4.800 mV

9.200 mV

17.00 mV

22.80 mV

17

7.000 mV

4.600 mV

8.600 mV

13.40 mV

22.00 mV

98

4.800 mV

9.200 mV

9.200 mV

13.00 mV

28.00 mV

128

6.800 mV

—

—

13.80 mV

—

Fan speed, temperatures and noise

The fan inside the Modecom Volcano 750 Gold started spinning right away as soon as the unit was powered on. In the first three tests, it was running just at about 730 RPM, but even later it stayed at mostly reasonable speeds. Thanks to the heatsink configuration it does not surprise me the primary side is reasonably cool though the secondary is in worse situation, as could be seen from the overloading test. As usually it is good to remind that high temperatures are not really good for capacitors, especially those terrible Teapo SCs in there.

Output %

Fan speed (RPM)

Temperature intake/ outtake

Noise (dBA)

3.9

729

20 °C/ 22 °C

39.0

20

730

20 °C/ 23 °C

39.0

40

733

21 °C/ 25 °C

39.0

60

765

22 °C/ 30 °C

39.5

80

1032

22 °C/ 31 °C

39.3

100

1383

22 °C/ 35 °C

41.0

CL 13

739

22 °C/ 25 °C

39.0

CL 17

739

22 °C/ 27 °C

39.0

CL 98

1343

22 °C/ 33 °C

41.0

OL 128

1464

24 °C/ 40 °C

41.8

The unit survived the Sweater contest fine though temperatures crossed 50 °C and the fan speed reached almost 1500 RPM. But all considered, the unit stays reasonably silent (@38.8 dBA ambient), more silent than I would have expected. It of course does not reach all those high-end models with semi-fanless operation or very slow spinning fan, but it is still better than many competing models in its price range for sure.